Agaricus blazei Murill is a mushroom largely consumed due to its medicinal properties. Effects of aqueous extract from its lineage AB97/11 in 2 fruiting body development stages (closed and opened pileus) were evaluated on chinese hamster V79 cells using cytokinesis blocking micronucleus (CBMN) and comet assays. The cells were treated at 0.15% concentration of aqueous extract prepared at different temperatures: ice-cold (4°C), room temperature (21°C) and warm (60°C). The extracts were applied in mutagenicity and antimutagenicity protocols (simultaneous, pre-incubation and continuous). The results showed that the aqueous extracts of Agaricus blazei lineage AB97/11 obtained at the 3 temperatures and both development stages did not present mutagenic or antimutagenic effect in V79 cells either in CBMN or comet assay.
Meiotic studies were carried out in 47 diverse germplasm lines of Panicum maximum and various chromosomal associations during diakinesis, metaphase and anaphase were recorded. All the accessions showed a uniform chromosome number of 2n=32. High variability for chromosome associations was recorded within as well as between different accessions. Number of combinations of chromosomal associations per accession ranged from 2 to 11, with 1–3 quadrivalents being most abundant. Average association, with the exception of IG 01-104 in which a few hexavalents were observed, varied from 0.2 IV+15.33 II+1.13 I (IG 97-07) to 2.13 IV+11.73 II (IG 97-14). Pooled data revealed 85.1% chromosomes to be associated as bivalents followed by 14.5, 0.25, 0.05 and 0.01% as quadrivalents, univalents, hexavalents and trivalents respectively. Average chromosomal association in germplasm was 0.002 VI+1.16 IV+0.01 III+13.62 II+0.08 I. Basic chromosome number of 8 is proposed for the germplasm lines based on meiotic configurations from these accessions. Previous views on basic chromosome number and auto-allopolyploid origin of P. maximum is discussed.
Aeginetia indica L. (Orobanchaceae) cultivated in the Botanical Garden of the University of Vienna was found to have n=60 chromosomes in pollen mitosis. Based on the single report for the whole genus of the haploid number n=15, the investigated plants are octoploid. The karyotype is bimodal, and up to 8 chromosomes with satellites are present in the haploid chromosome set. The high polyploidy of Aeginetia is discussed in the context of the karyological data of the whole family.
The characids belong to the greater freshwater fish family of the world with around 700 recognized species. Whithin this group the genus Astyanax includes several species with unclear phylogenetic relationships, showing a wide karyotypic diversity. In the highly endemic Iguaçu river basin these problems are also observed being distinguished 6 unnamed Astyanax species (A to F). In the present work were cytogenetically studied 2 populations of A. sp. C from the first plateau of the Iguaçu river (Paraná State, Brazil). Fishes of both populations are similar in chromosome number, having 2n=50, however were evidenced clear differences in C-banding and nucleolar organizing regions (NORs) patterns. With the use of the restriction enzyme Alu I were obtained the same results as C-bands. These results indicate the complexity of Astyanax and the importance of further taxonomic revisions joining morphological, cytogenetic and molecular approachings.
Three Sida spp. viz. S. acuta, S. rhombifolia var. rhomboidea, S. cordata and a putative hybrid between S. acuta and S. rhombifolia var. rhomboidea were cytogenetically investigated to elucidate their characteristic karyotypes. S. acuta and S. rhombifolia var. rhomboidea possessed 2n=28 and 2n=14 chromosomes, respectively. In S. cordata, 2n=32 and in the putative hybrid, 2n=28 chromosomes were observed. The total length of 2n chromosome complements in S. acuta and S. rhombifolia var. rhomboidea were 55.6 μm, and 35.7 μm, respectively. In S. cordata, total length of 2n chromosome complement was 47.4 μm and in the putative hybrid, 96.7 μm. Except the putative hybrid, all species had only metacentric chromosomes. On the other hand, the putative hybrid had 6 sub-metacentric (6 sm) and 22 metacentric (22 m) chromosomes. Four CMA-positive bands were found in S. acuta, S. cordata and the putative hybrid, whereas, 2 such bands occurred in S. rhombifolia var. rhomboidea. These banded regions were DAPI-negative, indicating their absolute GC-rich nature. Both DAPI-positive (9) and negative (4) bands were found in S. cordata. An analysis of these data indicates that each Sida species possesses a distinct karyotype. The different 2n chromosome number, centromeric formula, length of total chromosome complements and fluorescent banding pattern unequivocally indicate a separate taxonomic rank of the putative hybrid.
Cytogenetic studies were carried out on Rhamdella microcephala collected from the headwaters of the Machado river, a tributary of the Sapucaí river, Minas Gerais, Brazil. Sixteen specimens exhibited 2n=56 chromosomes, with 18 metacentrics, 30 submetacentrics and 8 subtelocentric-acrocentrics (FN=84). The nucleolar organizing regions (NORs) were identified in the interstitial position on the long arm of a submetacentric pair (pair 12). Chromomycin A3 staining evidenced only the NOR-bearing segments. Positive C-band segments were identified in a pericentromeric position in most of the chromosomes and the NOR-bearing segments were also C-band positive. Some aspects related to the chromosomal characteristics of Rhamdella microcephala are discussed.
The present study aims at determining the potential genetic damage of occupational exposure to electromagnetic field (EMF). The studied subjects are engineers and air traffic controllers exposed to radio frequency emitted from different instruments. Lymphocytes of exposed and control individuals were analyzed for structural and numerical chromosomal aberrations, sister chromatid exchanges, mitotic activity and cell kinetics. Cells with structural chromosomal aberrations were significantly increased in both engineers and air traffic controllers (p<0.001). Also, the number of aberrant cells with total numerical aberrations increased significantly in both exposed groups (p<0.001). Numerical aberrations were mainly hypodiploidy. The frequencies of SCEs in engineers and air traffic controllers were slightly increased over the control but this increase was not statistically significant. A decrease in mitotic activity was reported in EM field exposed engineers and air traffic controllers at statistically significant levels of p<0.01 and p<0.001, respectively. Exposure to EM field did not affect the cell kinetics in engineers and air traffic controllers.
Six autotriploids were isolated from the progeny of an M2 line of Capsicum annuum L. var. PC1 whose progenitor was an M1 semisterile (induced by 40 kR gamma-ray). These triploids were characterised by large sized dark green leaves, stomata, pollen, flower and fruit growth besides longer petioles and greater plant spread. Nevertheless, these bear fewer branches, shorter internodes, fewer fruits and seeds besides delayed growth and flowering compared to their M1 progenitor and the control. The mean chiasma frequencies in the triploids were significantly less than 1 1/2 times to that of their M1 progenitor and their control. Lower pollen and seed fertilities recorded in them was mostly due to meiotic abnormalities. The possible reasons for differences in morphometrics and cytological features in the autotriploids recorded earlier and now are suggested.
Cytomorphological studies including scanning electron microscopy of the seed surfaces and seed protein characterization have been performed to ascertain interrelationship between 2 species of Nigella (Ranunculaceae) namely, Nigella sativa L. (black cumin: spice of commerce) and Nigella damascena L. (love-in-a-mist: ornamental) and the results obtained have been discussed. Further, in this investigation it has also been noted that a line of N. damascena obtained from Royal Botanic Garden, Kew, London possessed unique ornamental phenotype and yielded good number of viable seeds per plant which were with high protein content.
Karyomorphological studies along with determination of chromosome number in some species of Anemone and Ranunculus (Ranunculaceae) have been made. The species observed include Anemone obtusiloba D. Don., A. obtusiloba subsp. omalocarpella Druhl., A. vitifolia Buch.-Ham., Ranunculus diffusus DC., R. laetus Wall. and R. sceleratus L. Four different types of chromosomes have been observed in R. diffusus, R. laetus and R. sceletatus. Satellited chromosomes have been observed in R. diffusus. In all the cases, chromosomes with centromeres at median regions outnumbered the rest. Chromosomes in all the taxa under present investigation except in R. sceleratus is considerably large and symmetrical showing primitiveness of the species.
Cytomixis was recorded during microsporogenesis in a tetraploid (2n=4x=48) genotype of spearmint (Mentha spicata L.), an aromatic plant of the family Lamiaceae. The phenomenon of cytomixis was observed in leptotene to pachytene stages of the first meiotic prophase. The migration of nuclear content involved all the chromosomes or part of the chromosomes of the donor cell. The occurrence of PMCs with chromosome numbers deviating from the tetraploid number (2n=48), derived from the process of cytomixis indicated the possibility of aneuploid and polyploid gamete production. The pollen fertility was found to be affected by this phenomenon and it seems possible that genetic factors might have also contributed towards the pollen sterility.
Recent investigations in this laboratory have lead to the formulation of the hypothesis that the mechanism of sister chromatid exchange formation does not involve breakage and rejoining of segments of chromosomes. According to the hypothesis, heterochromatin exists on the chromosome surface exclusively. Sister chromatid exchanges occur when this heterochromatin exists in an unstable state and sections are transposed or translocated between sister chromatids. In order to study this phenomenon further, cells from a high sister chromatid exchange frequency disorder, Bloom syndrome, were analyzed for the presence of unstable heterochromatin. In addition to confirming the presence of unstable heterochromatin, Bloom syndrome cells were often found to contain double minute chromosomes, and these were observed to form by accretion of unstable heterochromatin from the chromosome surface, possibly solving the enigma of their origin and formation.
Chromosomes of the Indian taxon of Crocidura horsfieldi, the Indian house shrew, Suncus murinus and the pigmy shrew, S. etruscus are analysed. The karyotype of C. horsfieldi, has 2n=38 and is compared with the karyotypes of other species of Crocidura. The house shrew, S. murinus has a general karyotype with 2n=40 and the variant karyotypes have 2n=30, 31, 32, and 37. The karyotype of the pigmy shrew, S. etruscus consists of 42 chromosomes. The karyotypes of Crocidura, the general karyotype of S. murinus and that of S. etruscus are compared with each other to understand their cytological nearness. The possible role of pericentric inversions and Robertsonin fusions in the karyotype evolution of different species of the 2 genera are discussed.
The ectal mandibular gland (EMG) of wasps is homologous to the mandibular gland of ants and bees. This gland belongs to salivary system and its function stile unknown. The EMG of Polistes versicolor showed histological and ultramorphological features similar to that founded in ants and others wasps. This gland is constituted by a secretory region and a reservoir. The secretory region contains individual secretory cells that showed several nucleoli. The reservoir has a club shape and is connected to each mandible, by a duct that opens on its external side, which there are cuticular projections. The EMG of males is smaller than those of females. Our results suggested that the EMG secrete volatiles compounds that are liberated when the mandibles still open.
In this study, the effects of aspirin (acetyl salicylic acid-ASA) on the third instar larvae salivary gland polytene chromosomes of Drosophila melanogaster have been investigated. The third instar larvae have been fed on medium containing ASA. In the polytene chromosome slides prepared from this larvae, some chromosomal aberrations, described as ectopic threads between different arms and banding regions were observed. The possible mechanisms of the ectopic pairing caused by ASA have been discussed.